MECHANICAL, THERMAL AND

MORPHOLOGICAL PROPERTIES OF

POLY(LACTIC ACID)/SUGARCANE BAGASSE

FIBER COMPOSITES

KHOO RONG ZE

UNIVERSITI SAINS MALAYSIA

2014

MECHANICAL, THERMAL AND MORPHOLOGICAL

PROPERTIES OF POLY(LACTIC ACID)/SUGARCANE BAGASSE

FIBER COMPOSITES

by

KHOO RONG ZE

Thesis submitted in fulfilment of the requirements

for the degree of

Master of Science

August 2014

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ACKNOWLEDGEMENT

First and foremost, I would like to express my greatest gratitude to my

supervisor Assoc. Prof. Dr. Chow Wen Shyang for his valuable advices,

encouragement and constant dedication throughout this whole research and thesis

writing. I am very grateful to have such a good and dedicated supervisor.

I would like to thank Dean Professor Dr. Hanafi Ismail, all lecturers and

administrative staffs for their kind cooperation and assistance. Thanks are also

extended to technical staffs, En. Mohd Faizal b. Mohd. Kassim, En. Muhammad Sofi

b. Jamil, En. Mohammad b. Hasan, En. Sharil Amir b. Saleh, En. Abdul Rashid b.

Selamat , Pn. Fong Lee Lee, En. Mokhtar b. Mohamad, En. Ahmad Rizal Abdul Rahim,

Cik Jamilah Afandi, Cik Nor Faizah Hamid and En. Hazhar Hassan for their assistance

and technical supports.

Last but not least, my sincere thanks are also extended to my parents, my

coursemates and my beloved friends for their support and encouragement.

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TABLES OF CONTENTS

ACKNOWLEDGEMENT…........................................................................................ii

TABLE OF CONTENT…...........................................................................................iii

LIST OF TABLES......................................................................................................vii

LIST OF FIGURES...................................................................................................viii

LIST OF ABBREVIATION........................................................................................xi

LIST OF SYMBOLS..................................................................................................xii

ABSTRAK................................................................................................................xiii

ABSTRACT..............................................................................................................xiv

CHAPTER 1 – INTRODUCTION............................................................................... 1

1.1 Research Background……………………………………………………...… 1

1.2 Problem Statement…………………………………………………………... 4

1.3 Research Objectives..........................................................................................5

1.4 Research Scopes................................................................................................5

1.5 Thesis Structure.................................................................................................6

CHAPTER 2 – LITERATURE REVIEW.................................................................... 7

2.1 Green Composites………………………………………...………………..... 7

2.2 Biodegradable Polymers…………………………………………...……….... 8

2.3 Natural Fibers..................................................................................................10

2.4 Natural Fibers Reinforced Composites............................................................11

2.4.1 Advantages of natural fiber reinforced composites............................. 12

2.4.2 Disadvantages of natural fiber reinforced composites.........................12

2.4.3 Effects of natural fiber types............................................................... 13

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2.4.4 Effects of natural fiber loading........................................................... 15

2.4.5 Effect of natural fiber length............................................................... 15

2.5 Poly(lactic acid).............................................................................................. 16

2.5.1 Advantages of PLA.............................................................................19

2.5.1(a) Environmental friendly......................................................... 19

2.5.1(b) Energy saving........................................................................19

2.5.1(c) Processibility..........................................................................19

2.5.1(d) Biocompatibility....................................................................19

2.5.2 Limitations of PLA............................................................................. 20

2.5.2(a) High brittleness......................................................................20

2.5.2(b) Poor thermal stability............................................................ 20

2.6 PLA/Natural Fiber Composites.......................................................................20

2.7 Sugarcane Bagasse......................................................................................... 21

2.7.1 Beneficial application of sugarcane bagasse (SCB) wastes.................23

2.7.2 Applications of sugarcane bagasse (SCB) wastes...............................24

2.8 Sugarcane Bagasse Fiber Treament.................................................................24

2.9 Toughness Improvement of PLA....................................................................26

2.9.1 Epoxidized soybean oil as impact modifier........................................ 28

2.10 Summary of Literature Review.......................................................................29

CHAPTER 3 – MATERIALS AND METHODS........................................................31

3.1 Materials.........................................................................................................31

3.1.1 Poly(lactic acid)..................................................................................31

3.1.2 Sugarcane Bagasse..............................................................................31

3.1.2(a) Treatment of sugarcane bagasse fiber.....................................31

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3.1.2(b) Preparation of sugarcane bagasse fiber powder (SCBFP)..... 33

3.1.3 Epoxidised soybean oil....................................................................... 34

3.2 Preparation of PLA/SCBF composites............................................................34

3.3 Materials characterization...............................................................................36

3.3.1 Impact test...........................................................................................36

3.3.2 Field emission scanning electron microscopy.....................................36

3.3.3 Thermal characterization.....................................................................36

3.3.3(a) Differential scanning calorimetry...........................................36

3.3.3(b) Dynamic mechanical analysis................................................37

3.3.3(c) Thermogravimetry analysis...................................................37

CHAPTER 4 – RESULTS AND DISCUSSION.........................................................38

4.1 Effects of fibre content on the impact properties and morphology of PLA

green composites.............................................................................................38

4.2 Effects of epoxidized soybean oil (ESO) on the impact properties

and morphology of PLA green composites......................................................43

4.3 Effects of fiber size on on the impact properties

and morphology of PLA green composites......................................................47

4.4 Thermal Properties PLA green composites.....................................................51

4.4.1 Dynamic Mechanical Analysis (DMA)...............................................51

4.4.1(a) Effects of SCBF content.........................................................51

4.4.1(b) Effects of ESO content on PLA/SCBF-10 composites...........54

4.4.1(c) Comparison between SCBF- and SCBFP- based

PLA composites........................................................56

4.4.2 Differential Scanning Calorimetry (DSC)...........................................57

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4.4.2(a) Effects of SCBF content ........................................................57

4.4.2(b) Effect of ESO content on PLA/SCBF-10 composites............60

4.4.2(c) Comparison between SCBF- and SCBFP-based PLA

Composites..............................................................................62

4.4.3 Thermogravimetry Analysis (TGA)....................................................63

4.4.3(a) Effects of SCBF content.........................................................63

4.4.3(b) Effects of ESO content on PLA/SCBF-10 composites...........66

4.4.3(c) Comparison between SCBF- and SCBFP-based PLA

Composites..............................................................................69

CHAPTER 5 – CONCLUSIONS AND RECOMMENDATIONS FOR

FUTURE STUDIES....................................................................................................71

5.1 Conculsions.....................................................................................................71

5.2 Recommendations for future studies...............................................................73

REFERENCES.............................................................................................................7

vii

LIST OF TABLES

Table 3.1 Typical properties of epoxidized soybean oil 34

Table 3.2 Material designation and composition for PLA/SCBF composites 35

Table 3.3 Processing parameters for compression moulding 35

Table 4.1 E’, tan δ peak value and Tg of PLA and PLA/SCBF composites 54

Table 4.2 E’, tan δ peak value and Tg of PLA/SCBF-10 at various ESO

loading 56

Table 4.3 E’, tan δ peak value and Tg of PLA composites 57

Table 4.4 Thermal characteristics of PLA and PLA/SCBF composites 59

Table 4.5 Thermal characteristics of PLA/SCBF-10 with various ESO

loading 61

Table 4.6 Thermal characteristics of PLA composites 62

Table 4.7 TGA results for PLA and PLA/SCBF composites 65

Table 4.8 TGA results for PLA/SCBF-10 containing different ESO loading 67

Table 4.9 TGA results of PLA/SCBF-10, PLA/SCBFP-10 composites 69

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LIST OF FIGURES

Figure 2.1 Classification of biodegradable polymers (John & Thomas, 2008). 8

Figure 2.2 Global biodegradable polymer market from year 2010 to 2016. 9

Figure 2.3 Structural constitution and arrangement of a natural fibre cell 11

(Dicker et al., 2014)

Figure 2.4 Influence of different natural fibres on (a) tensile and (b) Charpy 14

notched impact strength of PLA biocomposites (fibre content

30 wt%) (Bledzki et al., 2008)

Figure 2.5 Chemical structure of PLA 17

Figure 2.6 L(+) and D(-) stereoisomers of lactic acid 17

Figure 2.7 Synthetic production of PLA. 17

Figure 2.8 Several examples of PLA applications in market (Gotro, 2012). 18

Figure 2.9: (a)Sugarcane from local market and (b)sugarcane bagasse after

extraction of juice 22

Figure 2.10 Chemical composition of sugar cane bagasse (Loh et al., 2013) 23

Figure 2.11 Chemical linkages between lignin and cellulose

(Maryana et al., 2014) 25

Figure 2.12 Epoxidized soy bean oil (Campbell & Ramesh, 2004) 29

Figure 3.1 Sugarcane bagasse after drying for 24 hours 32

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Figure 3.2 Sugarcane bagasse fiber (SCBF) after alkaline treatment 32

Figure 3.3 Sugarcane bagasse fibre (SCBF) in 5mm length 32

Figure 3.4 Sugarcane bagasse fiber powder (SCBFP) 33

Figure 3.5 Chemical structure of ESO resin 34

Figure 4.1 Charpy impact strength of neat PLA and PLA/SCBF composites 39

Figure 4.2 FESEM micrograph taken from the impact fracture surface of

PLA 40

Figure 4.3 FESEM micrograph taken from the impact fracture surface

of PLA/SCBF-5 composites 41

Figure 4.4 FESEM micrograph taken from the impact fracture surface

of PLA/SCBF-10 composites 41

Figure 4.5 FESEM micrograph taken from the impact fracture surface

of PLA/SCBF-15 composites 42

Figure 4.6 Effects of ESO content on the Charpy impact strength of

PLA/SCBF composites 43

Figure 4.7 FESEM micrograph taken from the impact fracture surface

of PLA/SCBF-10/ESO-5 composites 46

Figure 4.8 FESEM micrograph taken from the impact fracture surface

of PLA/SCBF-10/ESO-10 composites 46

Figure 4.9 FESEM micrograph taken from the impact fracture surface

of PLA/SCBF-10/ESO-15 composites 47

Figure 4.10 Impact strength of PLA/SCBF and PLA/SCBFP composites 48

x

Figure 4.11 FESEM micrograph taken from the impact fracture

surface of PLA/SCBFP-10 composites 49

Figure 4.12 Impact strength of PLA/SCBF/ESO-10 and

PLA/SCBFP/ESO-10 composites 50

Figure 4.13 FESEM micrograph taken from the impact fracture surface

of PLA/SCBFP-10/ ESO-10 composites 51

Figure 4.14 E’ vs T traces of PLA/SCBF composites recorded from DMA 53

Figure 4.15 E” vs T traces of PLA/SCBF composites recorded from DMA 53

Figure 4.16 DSC curves for neat PLA and PLA/SCBF composites 58

Figure 4.17 DSC curves of PLA/SCBF-10 with various ESO loading 60

Figure 4.18 DSC curves of PLA/SCBFP-10 and PLA/SCBFP-10/ESO-10

composites 63

Figure 4.19 TGA curves for PLA and PLA/SCBF composites 65

Figure 4.20 DTG curves for PLA and PLA/SCBF composites 66

Figure 4.21 TGA curves for PLA/SCBF-10/ESO composites 68

Figure 4.22 DTG curves for PLA/SCBF-10/ESO composites 68

Figure 4.23 TGA curves of PLA/SCBF-10 and PLA/SCBFP-10 70

Figure 4.24 DTG curves of PLA/SCBF-10 and PLA/SCBFP-10 composites 70

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LIST OF ABBREVIATIONS

DMA dynamic mechanical analysis

DSC differential scanning calorimetry

ESO epoxidised soybean oil

EVA poly(ethylene-co-vinyl acetate)

FE-SEM field emission secondary electrom microscope

NaOH sodium hydroxide

PCL polycaprolactone

PEA polyesteramide

PHA polyhydroxyalkanoate

PHB poly(3-hydroxybutyrate)

phr part per hundred

PLA poly(lactic acid)

PLLA poly(L-lactide)

PP polypropylene

PVC polyvinyl chloride

SCB sugarcane bagasse

SCBF sugarcane bagasse fiber

SCBFP sugarcane bagasse fiber powder

SEM secondary electron microscope

TGA thermogravimetry analysis

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LIST OF SYMBOLS

E’ Storage modulus

E” Loss modulus

tan δ E”/E’ ratio

Tcc Cold crystallization temperature

Tg Glass transition temperature

Tm Melting temperature

Tonset Onset decomposition temperature

wt% Weight percentage

χc Degree of crystalinity

xiii

SIFAT MEKANIK, TERMA DAN MORFOLOGI KOMPOSIT POLI(ASID

LAKTIK)/GENTIAN HAMPAS TEBU

ABSTRAK

Komposit poli(asid laktik)/gentian hampas tebu (PLA/SCBF) disediakan dengan

menggunakan kaedah penyebatian leburan dan diikuti oleh pengacuanan mampatan.

Minyak kacang soya terepoksida (ESO) dipilih sebagai pemplastik bagi komposit

PLA/SCBF. Demi mengkaji kesan saiz gentian terhadap sifat-sifat komposit PLA,

SCBF yang dirawat alkali (~5 mm) telah dihancurkan ke dalam bentuk serbuk dan

dinamakan SCBFP (~500 μm). Sehubungan dengan itu, tiga parameter telah diselidik

dalam kajian ini, iaitu kandungan SCBF (5-15 wt%), muatan ESO (5-15 phr) dan kesan

SCBFP. Ujian hentaman Charpy digunakan untuk mengkaji kesan hentaman terhadap

komposit PLA sementara sifat morfologi dikaji dengan menggunakan mikroskop

electron penskanan pancaran medan (FESEM). Sifat terma komposit diperiksa dengan

penganalisa mekanik dinamik (DMA), kalorimeter pengimbasan pembezaan (DSC)

dan penganalisis thermogravimetrik (TGA). Kekuatan hentaman PLA telah

dikurangkan dengan penambahan SCBF. Walau bagaimanapun, kekuatan hentaman

komposit PLA/SCBF-10 telah ditingkatkan dengan kehadiran ESO disebabkan kesan

pemplastikan. Ujian DMA menunjukkan bahawa penambahan SCBF dapat

meningkatkan modulus simpanan (E’) PLA. Selain itu, SCBFP boleh mempertingkat

E’ dengan lebih ketara. Keputusan DSC menunjukkan bahawa SCBF dan SCBFP

menaikkan darjah penghabluran PLA. ESO telah menurunkan suhu peralihan kaca (Tg)

bagi komposit PLA. TGA menunjukkan bahawa kestabilan terma komposit

PLA/SCBFP adalah setara dengan PLA/SCBF.

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MECHANICAL, THERMAL AND MORPHOLOGICAL PROPERTIES OF

POLY(LACTIC ACID)/SUGARCANE BAGASSE FIBER COMPOSITES

ASTRACT

Poly(lactic acid)/sugarcane bagasse fiber (PLA/SCBF) composites were prepared

using melt compounding followed by compression molding. Epoxidized soybean oil

(ESO) was selected as plasticizer for the PLA/SCBF composites. In order to study the

effect of fiber size on the properties of PLA composites, alkali treated SCBF (5 mm

length) was grounded into powder form and designated as SCBFP (~500 μm).

Accordingly, three parameters were investigated in this research, i.e., SCBF content

(5-15 wt%), ESO loading (5-15 phr) and SCBFP effects. Impact properties of PLA

composites were characterized by Charpy impact test while morphological properties

were studied using field emission scanning electron microscopy (FESEM). Thermal

properties of the composites were examined with dynamic mechanical analysis

(DMA), differential scanning calorimetry (DSC) and thermogravimetry analysis

(TGA). The impact strength of PLA was reduced by the addition of SCBF.

Nevertheless, the impact strength of PLA/SCBF-10 composites was improved

significantly in the presence of ESO due to the plasticization effect. DMA results

showed that the addition of SCBF increased the storage modulus (E’) of PLA, and the

effect is more pronounced for the one containing SCBFP. From DSC, results showed

that SCBF and SCBFP increased degree of crystallinity of PLA. ESO was found to

decrease the glass transition temperature (Tg) of PLA composites. As for TGA, the

thermal stabilities of PLA/SCBFP composites are comparable to that of PLA/SCBF.

1

CHAPTER 1

INTRODUCTION

1.1 Research background

The awareness of preserving Mother Earth is increasing among people from all walks

of life. As global population continues to increase time by time, topics like greenhouse

gas emissions, toxicity and resource depletions are being emphasized lately.

Environmental friendly is one of the major attentions in manufacturing companies

when they are introducing products to market. In recent years, we have seen that green

products are emerging and slowly play an important part in our daily lives. Green

polymers are polymers that were produced using bio-based materials obtained from

plant sources (Gilfillan et al., 2012). We can see that they are replacing non-

biodegradable polymers that were involved in production of home appliances,

electronic devices, household cleaners and even production of vehicle parts

continuously.

In the field of polymer science and engineering, many studies are made

regarding different biodegradable polymers that could replace petroleum based

plastics in all kinds of application (Frone et al., 2013). In order to help reduce

environmental burden of the petroleum based polymer materials, development of bio-

based composites gained enormous interest in polymer community (Bajpai et al.,

2013). Green composites are one of the most attractive topics where composites can

be manufactured by adding various natural resources into polymers such as poly(lactic

acid) (PLA). The addition of natural fibers into polymer materials not only helps to

reduce environmental impact, they could also reduce the manufacturing cost and

increase commodity of the product.

2

Poly(lactic acid) (PLA) is an ecological aliphatic polyester obtained from lactic

acid (Ali et al., 2009). PLA, having extremely good mechanical properties, is produced

on a large scale from fermentation of corn starch to lactic acid and subsequent

polymerization. After being used for a longer period, pure PLA can be degraded into

carbon dioxide, water, and methane (Qin et al., 2011).

Since PLA is produced using natural resources, its degradation process only

involves simple hydrolysis of ester bond and does not require any assistance of

enzymes to activate this reaction (Garlotta, 2001). This contributes to wide application

of PLA in various fields like biomedical and packaging applications where the

materials can be disposed of easily without harming the environment. However, there

are some deficiencies of PLA that can affect its application, such as high production

cost, brittleness, low thermal stability, lower water vapour and gas barrier properties

(Frone et al., 2013; Shukor et al., 2014).

Consequently, reinforcement of PLA matrix had become the attention of many

researchers in order to improve overall properties of PLA. Many efforts had been done

to improve the characteristics of PLA in order to compete with low cost and flexible

commodity polymers. Various materials had been used to blend with PLA including

non-biodegradable polymers and biodegradable materials (Bajpai et al., 2013). A

simple way of improving the mechanical, physical and thermal properties of PLA is to

add natural fibers, such as banana fiber (Majhi et al., 2010), enzyme modified oil palm

fibers (Mamun et al., 2013), sugarcane bagasse residue (Wang et al., 2013) and olive

pit powder (Koutsumitopolou et al., 2014).

In general, natural fibers are able to enhance selected mechanical properties

(e.g., tensile strength, modulus, impact strength) of a biopolymer (Majhi et al., 2010;

Mukherjee & Kao, 2011). Graupner et al. (2009) stated that natural fiber reinforced

3

PLA had already made its way into market. For instance, biodegradable urns consisting

of PLA and flax that were produced by Jakob Winter (Satzung, Germany) by using

compression moulding method. Other examples include collaboration research of

NEC Corporation and UNITIKA LTD, developing bioplastic composites for mobile

phone shells that were made from PLA and 15-20% kenaf fibers. This shows that

PLA/natural fiber composites were indeed capable of providing many benefits for our

daily activities.

In the field of material science, converting biomass-derived waste into useful

and high valued materials is one of the most challenging topics recently (Moubarik et

al., 2013). Many natural wastes from plants were used or mixed to prepare different

types of material such as biodegradable polymers. One of the examples is the

sugarcane bagasse (SCB) that recently gained popularity among material researchers.

Bagasse is a natural residue that remains after sugarcane stalks are crushed to

extract their juice. The fact that SCB is often used as an ideal raw material is because

it can be easily obtained without much costing since they are wastes. The components

of SCB had been investigated and result showed that there are cellulose, hemicellulose,

lignin, ash and wax in the bagasse (Loh et al., 2013). These compositions make SCB

an ideal filler to be added to biopolymer such as PLA. PLA is considered as ‘green’

and eco-friendly polymeric material. Thus, hybridization of PLA and SCB is targeted

to produce a ‘green’ composite and will also be able to improve the physical and

chemical properties of PLA composites.

4

1.2 Problem statement

Although the bioplastics market is growing rapidly, the price of PLA is still relatively

high. Incorporating natural resources (as well as waste from natural resources) into the

matrix of PLA can be an alternative to reduce the cost of production where lesser PLA

will be used. In this research, alkali treated sugarcane bagasse fiber (SCBF) and

sugarcane bagasse fiber powder (SCBFP – which produced by grinding SCBF into

powder form) was added into PLA. The SCBF was selected because of its high

availability. Besides reducing the production cost of PLA composites, using SCBF as

filler material can also help to solve sugarcane bagasse waste problem. In other words,

converting waste into value added product.

Brittleness is one of the reason that limits the application of PLA (Bajpai et al.,

2013). Although PLA/SCBF composite is a good candidate for the development of

‘green’ composites, the brittleness and thermal stability of the PLA composites need

to be concerned. Toughening of PLA composites is necessary because impact strength

of PLA will be reduced when SCBF is added into PLA matrix. Similar results were

obtained by Nuthong et al. (2013) where addition of bamboo fiber, vetiver grass fiber

and coconut fiber reduced the impact strength of PLA. Thus, toughening of PLA/SCBF

composites is an important task, in order to widen the application of these green

composites.

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1.3 Research objectives

(a). To determine the effects of sugarcane bagasse fiber (SCBF) loading on the

mechanical, thermal and morphological properties of PLA.

(b). To compare the effects of SCBF and sugarcane bagasse fiber powder (SCBFP) on

the impact and thermal properties of PLA.

(c). To improve the impact strength and thermal properties of PLA/SCBF composites

by the addition of epoxidized soybean oil (ESO).

1.4 Research scopes

In this study, sugarcane bagasse fiber (SCBF) was first treated with alkali. Then the

SCBF was grounded into powder form (SCBFP). The PLA/SCBF (and PLA/SCBFP)

composites were prepared using internal mixer followed by compression molding. The

SCBF loading was increased in the range of 5, 10 and 15 wt%. The effects of SCBF

and SCBFP on the impact strength and thermal properties of PLA are studied. In order

to increase the impact strength of PLA/SCBF composites, epoxidized soybean oil

(ESO; at 5, 10, and 15%) is introduced. ESO has long been used as plasticizer for

polyvinyl chloride (PVC) compounds and chlorinated rubbers (Ali et al., 2008). Thus,

it is expected that the ESO could also be used to improve the impact properties of

PLA/SCBF composites. The impact strength of the PLA composites is studied using

Charpy impact tester. The thermal properties of the specimens are investigated using

differential scanning calorimeter (DSC), thermogravimetric analyzer (TGA) and

dynamic mechanical thermal analyzer (DMA). The morphological properties of the

PLA composites are examined by field-emission scanning electron microscopy

(FESEM).

6

1.5 Thesis structure

Chapter 1 introduces the development of PLA green composites. The problem

statement, scope of study and structure of thesis are included in this chapter.

Chapter 2 discusses the literature review of this study. The influence of different

parameters (example: types of fiber, fiber loading and length) were being studied and

discussed based on research done by other researchers.

Chapter 3 provides the information about the material and method used in this study.

The general description of the sample characterization methods such as impact test,

morphology assessment thermal analysis are given in this chapter.

Chapter 4 focuses on the experimental result and discussion. Further elaborations on

the effects of SCBF and SCBFP on the impact and thermal properties of PLA, as well

as the influence of ESO on the properties of PLA/SCBF (and PLA/SCBFP) composites

were provided in this chapter.

Chapter 5 summarizes the significant findings in this study. Suggestions for future

studies were also recommended.

7

CHAPTER 2

LITERATURE REVIEW

2.1 Green composites

The usage of natural fibres in thermoplastics and thermosets is now becoming a

growing trend among composite manufacturers (Faruk et al., 2012). The term ‘green

composite’ means composites fabricated by natural fibers or crops, which are eco-

friendly (John & Thomas, 2008). Besides environmental friendly, the other advantages

of green composites include the abundant availability of natural fiber, low cost and

higher bio-degradability. In general, they can decompose on its own without using

additional energy or resources.

A review done by Dicker et al. (2014) summarises the major properties and

also certain potential applications of green composites. In the review, they concluded

that green composites have good mechanical properties (e.g., good strength and

stiffness), environmental friendly (renewable, biodegradable, low embodied energy,

non-toxicity), low cost, and biocompatibility. However, some of the disadvantages of

green composites need to be mentioned, e.g., high water absorption, low durability,

and low toughness. Hence, there are still room for research and development on the

properties of green composites so that they can be put into good use in various

industries and applications.

2.2 Biodegradable polymers

Since environmental preservation became an important issue, biodegradable materials

are starting to gain popularity ranging from consumers to researchers. Biodegradable

technologies have then skyrocketed in just a few years and many materials with

biodegradable properties had been produced. Such materials include biodegradable

8

polymers that were derived from renewable resources. There are four families of

biodegradable polymers, where the first three families are produced from biomass. As

for the fourth family, they are obtained from fossil origin (see Figure 2.1). First family

consists of agro-polymers (e.g. polysaccharides) derived from biomass by

fractionation. For the second and third families, they are polyesters, respectively

produced by fermentation from biomass or from genetically modified plants (e.g.

polyhydroxyalkanoate (PHA)) and by synthesis from monomers obtained from

biomass (e.g. polylactic acid (PLA)). Lastly, the fourth family are polyesters, fully

manufactured by the petrochemical process (e.g. polycaprolactone (PCL);

polyesteramide (PEA); aliphatic or aromatic copolyesters) (John & Thomas, 2008).

Figure 2.1: Classification of biodegradable polymers (John & Thomas, 2008).

Many of these biodegradable polymers can be found and obtained

commercially. With a large range of promising properties, biodegradable polymers are

capable of competing with non-biodegradable polymers in various industrial fields

such as packaging and biomedical devices. This leads to a vast market and opportunity

9

for polymer manufacturers to explore the advantage and benefits of biodegradable

polymers. As seen in Figure 2.2, the global market of biodegradable polymers in 2010

was 771 million pounds. This amount is expected to increase significantly to nearly

932 million pounds in 2011 and will then further increase to 2.5 billion pounds in 2016.

These data shows the usage of biodegradable polymers had already been accepted and

applied in various industries, at a compound annual growth rate (CAGR) of 22% for

the 5-year period. At these rate, future of biodegradable materials especially polymers

shows great potential to be further developed and applied all over the world.

Figure 2.2: Global biodegradable polymer market from year 2010 to 2016 (Ruchika,

2012).